Since the launch of the scheme in July, over 60 projects have now come forward for talks with the Treasury about obtaining a UK Guarantee.

But just one scheme, a £1bn order for Crossrail rolling stock, has so far been underwritten by chief secretary to the Treasury Danny Alexander ahead of the Act coming into being.

Thames Water’s £3.6bn Thames Tideway sewer project is among the projects seeking backing.

The Bill passed through Parliament in just 55 days and now the Government can use its fiscal credibility to provide guarantees for major infrastructure projects that may struggle to raise finance.

Alexander said: “Securing Royal Assent just three months after the launch of the UK Guarantee scheme shows that we are getting on with delivering the vital infrastructure that the country needs to boost growth.

“Since July we’ve had significant interest from industry, and passed the legislation to make the scheme a reality.

“We can now get on with the search for eligible projects, and I hope today’s progress will encourage project sponsors to come forward to see how they can take advantage of the strength of the UK’s balance sheet by taking up a guarantee.”

The offer of guarantees will be awarded on a case by case basis and will be subject to due diligence and Parliamentary approval processes, and a commercial fee will be charged for any guarantee.